Mars is Ben Bova's love letter to space exploration; it's a novel-length booster for a manned Mars program. A very well-conceived and engaging (in places) novel, you should not read it expecting it to be space opera or really, any kind of adventure aside from the inevitable dangers of flying to another planet.
Mars stays strictly hard SF, so even when the possibility of life on Mars arises, you can be sure it won't come in the form of ancient cities and little red men, nor hazardous beasties who need to be shot or run from.
The main character is Jamie Waterman, a half-Navajo geologist who is a member of the first Mars expedition. The expedition is a multinational effort, with astronauts and scientists from every country that could afford to chip in. Much of the drama in the book involves the politics of the mission — the Russians and the Americans jealously keep track of how many astronauts of each country get to join the landing party, the Japanese astronauts are hyper-conscious of how they are representing their country, and the resident sexpot deliberately drives the Russians crazy by not sleeping with them because Russians killed her grandfather fifty years ago. Meanwhile, back home the founder of the Mars project is trying to balance concerns for the mission (including the fact that his own daughter is one of the scientists on Mars) with satisfying the politicians, in whose hands rest the decision to send more Mars expeditions or not. There are politics in space and on the ground, along with dossiers on each character that add depth to their backgrounds so that we understand why each one behaves the way they do on the mission.
That said, while the characters were each fleshed out and the story is compellingly plausible, with just enough hazards introduced to make the mission more than a long walk in space, it's a little spare as sci-fi goes. The major life-threatening situation that arises — a "Mars flu" that mysteriously afflicts everyone and stumps all the physicians trying to figure out its cause — has a clever forehead-smacking solution. There are hints of Martian life that don't really develop into much by the end of the book, though they are enough to whet the appetites of scientists, and readers of subsequent books in this series. There is some political intrigue between Jaimie Waterman, his ambitious journalist girlfriend back on Earth, and the opportunistic Vice President of the United States, each of them trying to get what they want from the other to advance their own agenda.
(I also feel compelled to point out that Bova, like most SF authors of his generation, presents a somewhat narrow range of female characters. Many of them are capable and three-dimensional, but there is the opportunistic journalist who has no qualms about sleeping her way to the top, there's the promiscuous scientist who takes malicious pleasure in giving the Russians blue balls by screwing everyone else, and there is the Vice President who is described as "shrill," "strident" and generally a conniving power-hungry bitch every time she appears.)
An enjoyable if slightly dry hard SF novel that should certainly go on your "Mars or Bust!" reading list. 3.5 stars - good book, though not very exciting.